Resolution enhancement of sigma-delta modulators using a tracking digital filter

This paper presents a sigma delta modulator architecture with enhanced resolution. The resolution enhancement is accomplished by means of a prediction filter that tracks the input signal, providing a dynamic range extension. The proposed architecture requires a conventional sigma delta modulator complemented by digital hardware and an extra DAC. It may be especially suitable for low voltage modulators operating at low oversampling ratios and, as a difference with MASH modulators, it does not require any filter matching.